Over the last 540 million years, the Earth has weathered three major ice ages — periods during which global temperatures plummeted, producing extensive ice sheets and glaciers that have stretched beyond the polar caps.

Now scientists at MIT, the University of California at Santa Barbara, and the University of California at Berkeley have identified the likely trigger for these ice ages.

In a study published in Science, the team reports that each of the last three major ice ages were preceded by tropical “arc-continent collisions” — tectonic pileups that occurred near the Earth’s equator, in which oceanic plates rode up over continental plates, exposing tens of thousands of kilometers of oceanic rock to a tropical environment.

The scientists say that the heat and humidity of the tropics likely triggered a chemical reaction between the rocks and the atmosphere. Specifically, the rocks’ calcium and magnesium reacted with atmospheric carbon dioxide, pulling the gas out of the atmosphere and permanently sequestering it in the form of carbonates such as limestone.

Over time, the researchers say, this weathering process, occurring over millions of square kilometers, could pull enough carbon dioxide out of the atmosphere to cool temperatures globally and ultimately set off an ice age.

“We think that arc-continent collisions at low latitudes are the trigger for global cooling,” says Oliver Jagoutz, an associate professor in MIT’s Department of Earth, Atmospheric, and Planetary Sciences. “This could occur over 1-5 million square kilometers, which sounds like a lot. But in reality, it’s a very thin strip of Earth, sitting in the right location, that can change the global climate.”

When an oceanic plate pushes up against a continental plate, the collision typically creates a mountain range of newly exposed rock. The fault zone along which the oceanic and continental plates collide is called a “suture.” Today, certain mountain ranges such as the Himalayas contain sutures that have migrated from their original collision points, as continents have shifted over millenia.

In 2016, Jagoutz and his colleagues retraced the movements of two sutures that today make up the Himalayas. They found that both sutures stemmed from the same tectonic migration. Eighty million years ago, as the supercontinent known as Gondwana moved north, part of the landmass was crushed against Eurasia, exposing a long line of oceanic rock and creating the first suture; 50 million years ago, another collision between the supercontinents created a second suture.

The team found that both collisions occurred in tropical zones near the equator, and both preceded global atmospheric cooling events by several million years — which is nearly instantaneous on a geologic timescale. After looking into the rates at which exposed oceanic rock, also known as ophiolites, could react with carbon dioxide in the tropics, the researchers concluded that, given their location and magnitude, both sutures could have indeed sequestered enough carbon dioxide to cool the atmosphere and trigger both ice ages.

Interestingly, they found that this process was likely responsible for ending both ice ages as well. Over millions of years, the oceanic rock that was available to react with the atmosphere eventually eroded away, replaced with new rock that took up far less carbon dioxide.

“We showed that this process can start and end glaciation,” Jagoutz says. “Then we wondered, how often does that work? If our hypothesis is correct, we should find that for every time there’s a cooling event, there are a lot of sutures in the tropics.”

Exposing Earth’s sutures

The researchers looked to see whether ice ages even further back in Earth’s history were associated with similar arc-continent collisions in the tropics. They performed an extensive literature search to compile the locations of all the major suture zones on Earth today, and then used a computer simulation of plate tectonics to reconstruct the movement of these suture zones, and the Earth’s continental and oceanic plates, back through time. In this way, they were able to pinpoint approximately where and when each suture originally formed, and how long each suture stretched.

They identified three periods over the last 540 million years in which major sutures, of about 10,000 kilometers in length, were formed in the tropics. Each of these periods coincided with each of three major, well-known ice ages, in the Late Ordovician (455 to 440 million years ago), the Permo-Carboniferous (335 to 280 million years ago), and the Cenozoic (35 million years ago to present day). Importantly, they found there were no ice ages or glaciation events during periods when major suture zones formed outside of the tropics.

“We found that every time there was a peak in the suture zone in the tropics, there was a glaciation event,” Jagoutz says. “So every time you get, say, 10,000 kilometers of sutures in the tropics, you get an ice age.”

He notes that a major suture zone, spanning about 10,000 kilometers, is still active today in Indonesia, and is possibly responsible for the Earth’s current glacial period and the appearance of extensive ice sheets at the poles.

This tropical zone includes some of the largest ophiolite bodies in the world and is currently one of the most efficient regions on Earth for absorbing and sequestering carbon dioxide. As global temperatures are climbing as a result of human-derived carbon dioxide, some scientists have proposed grinding up vast quantities of ophiolites and spreading the minerals throughout the equatorial belt, in an effort to speed up this natural cooling process.

But Jagoutz says the act of grinding up and transporting these materials could produce additional, unintended carbon emissions. And it’s unclear whether such measures could make any significant impact within our lifetimes.

“It’s a challenge to make this process work on human timescales,” Jagoutz says. “The Earth does this in a slow, geological process that has nothing to do with what we do to the Earth today. And it will neither harm us, nor save us.”

Well we were at 280ppm when burning fossil fuels saved the day albeit temporarily. Below 200ppm photosynthesis gets patchy to say the least. The plants you like to eat evolved when atmospheric CO2 was around 1500-2000ppm when the Earth was having a fantastic time!

So what happened to the Milankovic cycles?
If both correct it follows that the Milankovic cycles caused enhanced tectonic activity in tropics, which is very unlikely. During last million or so years there vere about 10 ice ages but they are taking about three coincidences in the last 500 million years. Forget it.

Milankovic cycles are not traceable back 300-400 Myr. Also such cycles primarily change insolation received in polar regions. And if such polar regions have limited ability for outside energy to enter (as the Arctic region today), then they can begin to ice, raise ice albedo, perhaps increase cloud cover, and cool the globe. Such past cycles did not induce glaciation in the southern polar regions as for the Arctic because conditions are not favorable.

Almost any GEO-Engineering attempt to “Cool” the climate over the course of a single lifespan would far more than likely result in triggering a Deep Ice Age as cooling like that would be far too fast for the Earths natural comtrol mechanisms to counter.

This is part of why we are currently in an Ice Age.
An Ice Age is not in distant past, it’s occurring now, and your Ice Age is probably one or the most coldest periods in Earth’s history.
I think of like this, during our Ice Age CO2, levels came close to being unable to sustain plant life, so unless you have periods of no plant life, it’s not going to colder than what it has been in last million years.
So we have low levels of CO2, and 400 ppm is still low, and during glacial periods CO2 levels dropped to around 180 ppm.
And 180 ppm is like humans breathing on Mt Everest- or knocking on death’s door [though some people have the genetics and are acclimated to survive it better].

Anyhow, it has long been accepted that weathering due to mountain building that has caused our present low levels of CO2.
But we in an Ice Age [again, long known] so entering Ice Age is not possible, though entering and a glacial period which is a common/normal part of your Ice Age, is possible.

Thank you for putting this in perspective.
Any person who simply examines the available data (ignoring hypotheses about why), can see that we are currently in one of those ice ages.
Note: By available data, I mean the fossil record, and the 5.5 million year ocean sediment record, and the 1 million year ice cores.

“the rocks’ calcium and magnesium reacted with atmospheric carbon dioxide, pulling the gas out of the atmosphere and permanently sequestering it in the form of carbonates such as limestone.”

But maybe YOU’VE got it right, it could be

– ice ages with miles thick glaciers further subduction, incl. sutura

AND

– lesser out gassing CO2 from cooling oceans

leading them to their misunderstanding / false conclusion that

” … calcium and magnesium reacted with atmospheric carbon dioxide, pulling the gas out of the atmosphere and permanently sequestering it in the form of carbonates such as limestone.”
_______________________________________________

Agree its nonsense. According to them land rising out of the ocean (due to tectonics) absorbs CO2 direct from the atmosphere and grows (sequesters) carbonates (limestone). So land exposed to the weather grows!! (Thats why the hills get taller and dont erode!!) This magic process would occur on current exposed land just as much as historic land. Strange we dont observe the current mountains sequestering CO2 and growing limestones (which have always formed under the oceans by the way!) before our eyes.
Hadnt noticed it was April 1st already! This paper must be on the shortlist for ‘Junk theory of the year’ award!

Yeah – were there any eye witnesses? Not to be too critical but it seems fashionable to discuss with certainty any theory that can’t be negated by objective measurement and then just expect us all to swallow it.

The ice core data shows temperature changes leading CO2 changes on shorter timescales. A more logical conclusion is that SO2 from large volcanoes dropped temperatures causing the ice ages referenced by this article.

This is assuming of course that the sensitivity of declining CO2 is the driver in creating ice ages, and not that CO2 reduction in the atmosphere is because of ice ages. It would appear that the latter is the actual scenario, especially in our most recent ice age climate the last 2.6 million years.

Yeah, I agree unfortunately. I was playing golf with a full professor about 12 years ago and he told me putting any reference to potential global warming impact GREATLY increased the chances of funding and/or publication. I am a geologist, and he was a biology professor at a large university. I debated with him a bit on the ethics of that, since in my view the bigger picture was that it was potentially ruinous to science and science education/communication to the public. He said it was debatable, and on top of that he had kids to put through college, a mortgage, retirement, etc. etc. to consider … yada yada yada … and that is just the way the world’s “PC” is right now. Unfortunately, I think we were both right.

“Thus I saw that most men only care for science so far as they get a living by it, and that they worship even error when it affords them a subsistence.”
– Johann Wolfgang

“We’ve got to ride this global warming issue.Even if the theory of global warming is wrong,
we will be doing the right thing in terms of
economic and environmental policy.”
– Timothy Wirth, President of the UN Foundation

From the article: “… could pull enough carbon dioxide out of the atmosphere to cool temperatures globally and ultimately set off an ice age”

Imagine if we could measure the energy CO2 is reflecting back to the surface. If we could measure it, then we could model it.

We’re told that the energy reflected from CO2 back to the surface is enough to control Ice Ages, and CO2 continues to keep the surface about 60F warmer than it would be without it, AND WE CAN”T MEASURE IT??? If we can’t measure it, how do we know it exists?

When I walk into the shade on a sunny day I can feel an immediate difference. Why can’t I feel the same thing when I walk into the shade from all the CO2?

Thomas,
We can and do directly measure thermal radiation from the atmosphere directed downwards.
It is at a completely different wavelength to incoming solar radiation so we know that it is
caused by the greenhouse effect. And this can be easily modeled using the known radiative
equations for the gases in the atmosphere.

For almost 30 years the “Baseline Surface Radiation Network” first proposed in 1990 by the World Climate Research Program, has been monitoring and gathering this data.
Here: https://bsrn.awi.de/

Note that in the project background they make the following comment:
“While a small change in irradiance at the Earth’s surface may cause a profound change in climate, the existing radiometric network is not capable of arriving at the required accuracy for climate research. In fact our present understanding of the radiation distribution both – horizontally and vertically – is not sufficient to understand the present climate. The simulation of the past and future climate changes, which would be induced by the change in radiation, is even more uncertain. ”

So yes we can and do measure down welling long wave radiation at the surface of the earth but any potential signal from anthropogenic co2 has yet to be seen since it would be (and is) swamped out by natural variation.

I actually do not have a problem with the belief that a lot of CO2 was captured…just hat it made much of a difference. Continents moving into each other could have effected rain patterns, ocean currents, volcanism, etc.

If I see proof that CO2 dropped and then temperature followed – that is a good chunk of evidence. When I see temperatures falling, and then CO2 dropping – well then they got cause and effect backwards.

I would have to go back and research but I thought; 1) that at least some ice ages occurred pretty quickly, like over decades, and 2) that CO2 was pretty high during some of the ice ages. I may be wrong, but if I am correct then this study doesn’t seem correct.

I would consider the formation of the Southern Ocean, with clear circulation around Antarctica, and the closing of the Panama seaway to have had rather more influence on the current glacial epoch than CO2 levels.

This is exactly the way I learned about the onset of the current ice age (starting some 3 million years ago). When the Isthmus of Panama silted over the flow of warm water from the Pacific to the Atlantic was cut off.

I imagine these rent seekers thought … “Now how might we get the magic CO2 golden goose mixed in with accepted ideas on plate tectonics? Just let your imaginations run wild guys.” The reality of evidence, however, shows that CO2 and temperature have been anti-correlated as often as they have been correlated throughout the history of major ice ages.http://edberry.com/SiteDocs/2010/10/EarthHistory1.jpg

To my knowledge there are essentially five explanations to Ice Ages that are considered by scientists. Two are endogenous and three exogenous.

Endogenous:
1. Tectonic causes
2. Greenhouse gases causes

Exogenous:
3. Changes in the Sun
4. Changes in the orbit of the Earth
5. Changes in the galactic environment of the Solar System

The articled presented in this post is just a not particularly convincing combination of 1 and 2.

The thing is that the dating of ice ages is quite good. And it is:
~450 Ma Andean-Saharan (Late Ordovician)
~300 Ma Karoo (Late Carboniferous)
~0 Ma Late Cenozoic

And there is a cool period in Jurassic-Early Cretaceous at ~150 Ma

I don’t believe in coincidences. It is clear that tectonics affects hugely the severity of an ice age. Formation of supercontinents favors strong cooling while rifting apart favors warming, but it is hard to imagine a 150 Myr tectonic cycle, although not impossible.

A 150 Myr GHG cycle is unthinkable unless driven by tectonics, that’s why there are attempts to link both.

A 150 Myr cycle in the Sun is unsupported by plasma physics. But who knows. It is unsupported by the main sequence, though.

A 150 Myr orbital cycle is possible but absolutely unknown. We are very uncertain about how the orbits evolve over such long times.

A 150 Myr galactic environment is easier to imagine but absolutely unsupported by evidence despite Nir Shaviv. We don’t know where the galactic arms were 150 Myr ago.

So in essence we have no idea of what causes ice ages. The title of this post is incorrect. There are no findings on what caused the ice ages, just proposals based on thinks that happened at the right time and could have affected climate. If they are ingenious, by the right people, and according to the scientific fashion of the moment (now CO2) they get well published and amply disseminated by the media. But that doesn’t mean that they have solved anything. In most cases they introduce more doubts than solve.

Turn Shaviv’s argument around – the planet is actually a galactic “arm” sensor.
Still the “arms are likely stellar density waves where the occupants change all the time.
Shaviv also got the 30Myr bobbing galactic shock wave motion right.

The Ca and Mg were already oxidized to their 2+ state. So if they sequestered CO2, that reaction would have to have a favorable equilibrium constant, and would also release some other material as part of a metathesis reaction.

So if it were MgCl2 and CaCl2 to start, it would generate HCl and we’d see the ocean pH drop like crazy (did it?). If it were Mg(OH)2 and Ca(OH)2, then the CaCO3 could form, but MgCO3 would not.

Establishing equilibria among all of these species is a complex task, but can be done.

There is a lot of chemical data that could be used to corroborate or invalidate this hypothesis, but doesn’t seem like they looked into that. Shouldn’t have been published without doing so.

I thought that when an oceanic plate collides with a ‘land’ plate/mass the oceanic one goes underneath the land one. It is called a suduction process/zone. It is because the specific mass of the oceanic plate is larger(?). So the oceanic crust never comes to the surface to absorb the CO2.

Slivers of oceanic crust are often broken off during the collision and emplaced in among the bottom sediment “scraped off” to form mountains. These slivers are called “ophiolites” or “ophiolite suites” because serpentine (metamorphosed ultramafic rocks) are often an important part. Serpentine rocks are greenish, mottled and shiny, somewhat similar to snake skin, hence the names. Serpens = latin for snake, Ophiolithos = greek for snake-rock.

If it was CO2 being drawn from the atmosphere that brought on ice ages, the levels of CO2 would have to have been much lower than now. Since we are really in a CO2 impoverished state at present, would not all photosynthetic plants have become extinct? Is there evidence that green plants had to re-evolve after each ice age? Same with all animals since they depend upon green plants. Sounds like BS to me.

As usual, in their zeal to attribute to CO2, they fail to apply the same logic that they muster to caution the benefits of grinding ophiolite. The forces that drive plate collisions and maintain their sutures at high elevation produce vast amounts of CO2.

Basically the middle is very hot and the outside is cool so you have a temperature gradient.
Why is the middle hot?…

The heat driving mantle convection has three sources. “Primordial” heat (left over from the accretion and differentiation that led to the formation of Earth’s core) contributes 20 to 50% of the heat. Heating due to the decay of radioactive isotopes (mainly potassium, thorium, and uranium) contributes 50 to 80%. Thirdly, tidal friction from the Moon’s pull on the Earth contributes perhaps 10%. Mantle convection is the main mechanism by which this heat escapes from the interior of Earth.

@Javier
From the perspective of an experienced chemist like myself, you do reealize that I can easily prove to you that are also cooling effects of more CO2 in the atmosphere?
So what is more: the cooling effects or the warming effects
Do you have some papers on that?

It is an exception and due to the same mechanism that warms the atmosphere elsewhere. Antarctica surface is actually cooler than the atmosphere temperature at the height where effective emission takes place, which is much lower at the poles. If correct it supports that CO2 must have some warming effect on the planet.

The second link goes to a low resolution graphic.
The note at the bottom of the graphic states:
“… Shown also are the radiances of blackbodies at several temperatures. a) Sahara Region; b) Mediterranean; c) Antarctic”

By that wording, the excerpt you post has another graphic of thermal emissions and these are comparison “blackbody” calculated temperature graphics for comparison, not actual measurements.

Nor is evident from the graphics exactly where CO₂ thermal emissions are identified.

There is a slight increase of thermal emissions near where CO₂ is active, but H₂O is also active over that frequencies.
Even at Antarctic levels of dry air,there is still more atmospheric water vapor than CO₂.

Henry, I am skeptical of your evidence. There are probably tens of thousands of experienced chemists and thousands of them with ample atmospheric expertise. Any particular reason I should trust you?

And when we are discussing about events that took place hundreds of millions of years ago, I become hyperskeptical, because the evidence to support people’s beliefs is rarely there.

There is good geological evidence about past Ice Ages, and fair proxy evidence that two of them might have had quite low CO2 levels. And that is about it. All the rest is insufficiently supported hypotheses.

Hence, as I think Ian Wilson correctly reported, there is a lag time of about 800 (?) years on average before increased warmth on earth shows up as increased CO2 in the atmosphere.

To give you some clues as on how you can see that CO2 is also cooling the atmosphere:

1) we can identify and quantify CO2 presence on other planets by measuring the deflections by CO2 of sunlight in the UV range.
2) we can see the deflections caused by CO2 in the 1-2 um range. Follow the green line fig. 6 bottom and see how it returns to us, picked up via the moon, in fig 7.
3) I know that CO2 has big absoprtion between 4 and 5 um because we used to measure CO2 in nitrogen at 4.6 um.

So, to sum it up, we know that CO2 has absorption in the 14-15 um range causing some warming (by re-radiating earthshine) but as shown and proved above it also has a number of absorptions in the 0-5 um range causing cooling (by re-radiating sunshine). This cooling happens at all levels where the sunshine hits on the carbon dioxide same as the earthshine. The way from the bottom to the top is the same as from top to the bottom. So, my question is: how much cooling and how much warming is caused by the CO2? How was the experiment done to determine this and where are the test results?

{Arrhenius and Tyndall only saw half of what was happening as they performed closed box experiments. I hope you see now why their science was not complete?

Anyway, I therefore did some emprrical experiements to find there is no warming caused by more CO2. Click on my name to read my report on that.

Sorry, you need this paper to show the deflections of CO2 in the 1-2 um. Try and understand the paper, as it provces conclsusively that CO2 is also cooling the atmosphere by deflecting certain sunlight away to space.

Re-radiation of incoming solar radiation is non-controversial. An atmosphere with GHGs is less transparent to incoming solar radiation, but what matters is the balance between Absorbed Shortwave Radiation (ASR) at surface and Outgoing Longwave Radiation (OLR) at top of the atmosphere. How increases in CO2 alter that balance determine the temperature effect, regardless of its effect reflecting incoming solar radiation.

Everything you say is known as far as I know. The question is that we are not capable of quantifying the CO2 effect, neither at warming nor at cooling. However theory and evidence indicate that warming dominates and the increase in CO2 has some unquantified net warming effect. If you disagree with that you should be able to prove it and publish it, because otherwise it just constitutes opinion.

it was you who said that you believe that there is an effect of warming by CO2 and that the net effect of more CO2 in the atmosphere is that of warming rather than cooling. Then you must submit to me the evidence for this and not put the onus on me to produce it? Anyway, I cannot think of a test to quantify whether the net effect of the re-radiations by CO2 is that of warming or cooling. But I did my own testing to find that there is no man made warming or that it is so small so as to be immeasurable compared to the natural factors at work. Click on my name to read my finla report on that. You are now admitting that nobody has a balance sheet showing exactly how much cooling and warming is caused by the CO2. That is a step forward.
We could have figured out easily that the effect by CO2 is nothing since it only increased from 0.03% to 0.04% over the last 50 years which is a change of only 0.01% in the atmosphere. By contrast water vapor can be about 0.5% but I think it may vary upward or downward by as much as 0.1% depending on
1) irradiation of the oceans by the sun
2) the weather
3) where to measure?
4) The amount of aeroplanes in the air making contrails
5) increased irrigations
6) cooling nuclear/gas fired/ coal fired power stations & other big factories etc
7) increased landuse – changing deserts (e.g. Las Vegas, Johannesburg)

to name but a few things that I can think influencing the amount of water vapor in the air….

Over time, the researchers say, this weathering process, occurring over millions of square kilometers, could pull enough carbon dioxide out of the atmosphere to cool temperatures globally and ultimately set off an ice age.

End of reading. Full stop. Deep breath… CO₂ IS NOT THE CONTROL KNOB!!!!!!

I didn’t have to read another word after that. This is what passes of study today?!?! Where and how do these people get a degree? Who are their advisors to allow them to even pursue such easily refuted garbage? A new idea that runs counter to accepted teachings is one thing, but it needs to have at least a little actual science behind it, something that can be proven/disproven, and a valid, solid experimental design! What is this bulls***??? SMH

@Javier
From the perspective of an experienced chemist like myself, you do reealize that I can easily prove to you that are also cooling effects of more CO2 in the atmosphere?
So what is more: the cooling effects or the warming effects
Do you have some papers on that?

“scientists say that the heat and humidity of the tropics likely triggered a chemical reaction between the rocks and the atmosphere. Specifically, the rocks’ calcium and magnesium reacted with atmospheric carbon dioxide, pulling the gas out of the atmosphere and permanently sequestering it in the form of carbonates such as limestone”

Calcium and magnesium in rocks?

Magnesium in rocks, e.g. magnesium carbonate, i.e. chalk is from the accumulated deposited shells of coccolithophores.

Yet, this calcium/magnesium sheds their carbon dioxide to rip CO₂ from the atmosphere?

“team found that both collisions occurred in tropical zones near the equator, and both preceded global atmospheric cooling events by several million years — which is nearly instantaneous on a geologic timescale. After looking into the rates at which exposed oceanic rock, also known as ophiolites, could react with carbon dioxide in the tropics, the researchers concluded that, given their location and magnitude”

Several million years gets conflated with “nearly instantaneous” geology bafflegab.

“We showed that this process can start and end glaciation,” Jagoutz says. “Then we wondered, how often does that work? If our hypothesis is correct, we should find that for every time there’s a cooling event, there are a lot of sutures in the tropics”

“We showed that this process can start and end glaciation”; er, no; “they” assumed but did not demonstrate.

“They performed an extensive literature search to compile the locations of all the major suture zones on Earth today, and then used a computer simulation of plate tectonics to reconstruct the movement of these suture zones”

No, it goes underneath, but part of the softer and lighter sediments on top of the oceanic plate usually gets “scraped off” and builds up against the continental plate. The “Franciscan melange” in CA is a beautiful example. It is one big scrunched up mess:

So the dramatic obstruction to the Earth’s massive atmospheric and oceanic heat distribution systems are of no consequence? You can arrange the continents any way you like and global average temperatures will remain the same?

Glaciations are rather short and start and end rather abruptly and are rather obviously controlled by orbital mechanics.

But glacial epochs are much longer. The present one has already lasted for 35 million years. That said, it did start rather abruptly at the Eocene/Oligocene border (the “Grande Coupure”), probably within a few hundred thousand years.

There is actually a much simpler explanation for the low CO2 during the Carboniferous-Permian. The Carboniferous isn’t called carboniferous for nothing. Huge amounts of coal were deposited during this interval, probably because efficient decomposers that “eat” dead vegetation had not yet evolved. This is a straightforward process with no need for hypothetical weathering processes.

The trouble with this hypothesis is that during the Cretaceous even more carbon was taken out of the atmosphere by the formation of huge volumes of chalk and world-wide emplacement of organics-rich shale in the oceans (most oil is Cretaceous). But the climate stayed extremely warm.

Did some quick research on this hypothesis. Easy to find two BIG qualitative problems with this extension of ‘CO2 as the climate control knob’ on geological time scales.

First, ophiolites ( basaltic ocean crust thrust up and exposed onto continental crusts) do exist. The form at the techtonic beginning of a subduction zone. BUT they are comparatively narrow so small in area. Extremely doubtful they could affect CO2 so much, especially since subduction zones recycle carbonate rocks into CO2 via heating and volcanism. And since the chemistry of actual ophilites does not show so much oxidation.

Second, ophiolites formed as landmasses wandered, meaning ocean circulations were very different. Ocean circulation governs planetary heat content, because that is where the bulk of heat resides, based simply on thermal mass. The present ‘ice ages’ starting about 2.5mya are thought to have been triggered by formation of the Panama isthmus at that time, drastically altering circulation exchange between the Atlantic and Pacific oceans.

If anything coincides with CO2 then by definition CO2 must be the causal factor. This is just another feeble attempt to terrify children. Like that arch dope George Monbiot who today claimed we were on track for a 4 C degree rise in temperature this century on an ever compliant BBC.

https://i.postimg.cc/PxXRvP0c/F2-large-1-copy.jpg
Accompanying Figure legend:Phanerozoic suture length in the tropics compared to the latitudinal extent of continental glaciation.
(A) Total length of active suture length. (B) Total length of active sutures that are reconstructed to be within 10°, 15°, and 20° of the equator over the past 520 million years. (C) Blue marks the latitudinal extent of continental ice sheets, excluding Alpine glaciers (table S3).

My thoughts:
Their proposition is entirely plausible to the extent of necessary but not sufficient to explain the totality of the global temperature decrease of the Quaternary compared to past glaciations.
Their Tropical suture hypothesis ignores the likely huge contribution to cooling the global climate of the current polar-centered location of the Antarctic continental land-mass, as well as a possible smaller role for the closing of the Panama Isthmus between the Atlantic and Pacific.
But it is the near CO2 starvation of the last Pleistocene LGM (around 180 ppm by some proxies) that should give the serious scientist pause. For that should come with a realization that humanity’s recent addition of CO2 (by digging up fossil fuels and burning them) may one day be properly viewed as a saving grace for the biosphere and all higher life on this planet.

They will entertain no other theory except those that show CO2 as a driver of climate. I’m not saying that tectonics don’t play a role in ice ages, but CO2 isn’t the mechanism. It’s been shown many times that CO2 changes is the effect, not the cause, of temperature change.

That may not be correct. According to Frozen Earth, a book by geologist Douglass MacDougal about the ice ages, an open pole can radiate more heat to space and this was involved in at least one of the ice ages. A more likely cause is equatorial mountain building which causes tropical ice. The ice over the poles does not reflect much sunlight to space. They actually slow the rate of cooling of the earth.

“Interestingly, they found that this process was likely responsible for ending both ice ages as well. Over millions of years, the oceanic rock that was available to react with the atmosphere eventually eroded away, replaced with new rock that took up far less carbon dioxide.”

OK, if the atmospheric CO2 was geologically sequestered, where did the replenishment come from to end the glaciations? This detail is overlooked!

Let me get this straight.
During the ice-ages, there were large tropical regions of oceanic/continental convergence, leading to regions of oceanic crust exposed, adjacent to large mountainous regions. The mountainous regions would have accumulated significant amounts of tropical ice, which would then increase earth’s albedo. The tropics normally receive the bulk of Earth’s direct insolation (sunlight). The mountains would then have large ice fields in these areas that would have reflected this insolation back into space. Therefore we can conclude that this tectonic activity in the tropics resulted in the initiation of past ice-ages because… Carbon Dioxide!
Did I get that about right? Just trying to make sure I’ve got a good handle on the science.

Almost. I think wooly mammoth farts or T-Rex belches were involved somewhere. Something to do with the tippy-dippy continental plates upsetting their tummies… up and down, up and down, up and down. It’s like sea sickness except the period between waves and troughs is a tad longer.

The CO2 climate cult strikes again. Their mechanism is only off by a few million years, or is it 10 million years, or eh 20 million years, and completely ignores the fact that temperatures decreased before CO2 levels.

HMM … continents wandering about for no particular reason — riding over and subducting as whimsy takes them. Makes perfect sense to me. I can’t imagine that solar fluctuations would have any effect on climate at all.

” … As global temperatures are climbing as a result of human-derived carbon dioxide, some scientists have proposed grinding up vast quantities of ophiolites and spreading the minerals throughout the equatorial belt, in an effort to speed up this natural cooling process. … ”

—

This is right up there with the dumbest things that have ever been penned, a contender for the 2019 Darwin Awards.

“What happens to the Trade Winds and energy distribution when mountains rise up in the tropics?”

My thoughts entirely.
Pesky mountains getting in the way of the wind, collecting all that white snow, altering the tropical albedo, reducing energy collection, replacing a previous warm tropical ocean with newly formed ice-filled mountains.
That can’t be it. Can it?

The take away from this study is, never let scientific facts get in the way of your imagination.
I guess the guiding principle here was, CO2 is responsible for dramatic climate change now what mechanism can we deploy to make it seem plausible?
I suppose the fact CO2 reacts to temperature change but has no significant impact on it, was ignored for the purpose of this research.

Kelemen and his partner geochemist Juerg Matter (a Lamont adjunct, now based at the University of Southampton) have found that many carbonate veins here actually formed during human time, and that the process is ongoing and fast. “It happens about 100,000 times faster than we thought,” said Kelemen. They also found that the reactions take place much deeper underground than previously thought, well below the surface where CO2 travels in groundwater through cracks.

Kelemen and Matter estimate that each cubic kilometer of peridotite naturally absorbs on average a ton of atmospheric carbon each year–up to 100,000 tons annually in the region. In places, the reaction has completely run its course; the rocks are fractured down to the tiniest pore spaces and filled with carbonate, creating entire mountains of the stuff. Theoretically, they say, there is enough peridotite in Oman and the neighboring United Arab Emirates to absorb 33 trillion tons of CO2—1,000 years of human output, if present-day emission rates remained unchanged.

In Cambrian, CO2 went up from 5000 ppm to 7000 and back to 5000 while temperature remained flat. In Silurian, the ice age ended when CO2 dropped from 4500 to 3000 ppm. In Cretaceous, warm climate persisted when CO2 dropped from 2000 to below 1000 ppm. Correlation is not causation but even the correlation is poor.

Then a couple of little but probably intense glaciations during the Ediacaran…
Gaskiers glaciation 580Mya
Baykonurian glaciation 547Mya

There’s probably a few others
Are these all a result of continental collisions near the equator ?

Not likely.
It’s a simplistic proposition, perhaps a factor, but ignores the wide range of other factors that lead to an ice age
[http://theconversation.com/ice-ages-have-been-linked-to-the-earths-wobbly-orbit-but-when-is-the-next-one-70069]. It also assumes that CO2 is the main driver of climate.

GregK, over very long time scales, earth’s axial tilt variability, orbital obliquity variability, distance of moon from earth (closer going back in time), length of day (decreasing backward in time), solar energy output (generally decreasing backward in time) might also be factors. We don’t know how the axis of Venus completely flipped over. We can’t assume that earth’s axis has always been close to what it has been in the last few million years, and continental drift might even have an influence on axial tilt.

Hence, as I think Ian Wilson correctly reported, there is a lag time of about 800 (?) years on average before increased warmth on earth shows up as increased CO2 in the atmosphere.

To give you some clues as on how you can see that CO2 is also cooling the atmosphere:

1) we can identify and quantify CO2 presence on other planets by measuring the deflections by CO2 of sunlight in the UV range.
2) we can see the deflections caused by CO2 in the 1-2 um range. Follow the green line fig. 6 bottom and see how it returns to us, picked up via the moon, in fig 7.
3) I know that CO2 has big absoprtion between 4 and 5 um because we used to measure CO2 in nitrogen at 4.6 um.

So, to sum it up, we know that CO2 has absorption in the 14-15 um range causing some warming (by re-radiating earthshine) but as shown and proved above it also has a number of absorptions in the 0-5 um range causing cooling (by re-radiating sunshine). This cooling happens at all levels where the sunshine hits on the carbon dioxide same as the earthshine. The way from the bottom to the top is the same as from top to the bottom. So, my question is: how much cooling and how much warming is caused by the CO2? How was the experiment done to determine this and where are the test results?

{Arrhenius and Tyndall only saw half of what was happening as they performed closed box experiments. I hope you see now why their science was not complete?

Anyway, I therefore did some emprrical experiements to find there is no warming caused by more CO2. Click on my name to read my report on that.

Sorry, you need this paper to show the deflections of CO2 in the 1-2 um. Try and understand the paper, as it provces conclsusively that CO2 is also cooling the atmosphere by deflecting certain sunlight away to space.

Sorry, you need this paper to show the deflections of CO2 in the 1-2 um. Try and understand the paper, as it provces conclsusively that CO2 is also cooling the atmosphere by deflecting certain sunlight away to space.

I have shown or tried to show that CO2 has a number of absorptions in the 0-5 um range where the sun emits. This means that CO2 deflects certain sunlight away from us causing cooling. There is only one absorption 14-15 um where the earth emits and it is in fact low energy radiation, being trapped on earth, [I think] much lower than all the radiation 0-5 um back radiated to space by the CO2. Note that water vapor also emits in that very same range. Looking for someone or something to blame, they falsely accused CO2 on which all life depends. How ironic is that? They complain about 0.01% CO2? It is evil?
So the net effect of more CO2 is zero at best and probably some cooling.
I have done empirrical tests to find that globally, minimum temperatures are dropping which is not in line with AGW theory. What my results mean: there is no man made global warming. Click on my name to read my final report on that.

Carbon Dioxide conducts temperatures on both hot and cold air on the planet. This causes an averaging out of temperatures at the pole and at the equator and all points in between.
Rising temperatures release huge amounts of weight in the form of ice melting. The liquid water distributes.
The release of the weight will cause geological change. It may be in the form of earthquakes, volcanoes, and sudden changes in temperature all over the globe.
Thus Siberia went from semi-tropical to arctic over night.
There is nothing new. It will happen again in various areas of the Earth.
Continents float on a molten lava mass. With the release of that ice weight a lot of changes will occur.
The most dramatic is likely to be a release of pressure caused by super volcanoes. That in itself is worse than any hydrogen bomb.
It has all ready happened locally in Washington State at St. Helens.
It is likely to happen soon at Yellowstone.
Volcanoes long dormant all over the planet are starting to wake up.
Again it is possible the release of weight on the continents may have something to do with that. We simply do not really know.
Our scientists are afraid to take a stand because their livelyhood does depend on what they say.

Richard Dawkins pointed out (Ancestor’s Tale) that when following the direct ancestral route, changes are so gradual that no ‘speciation’ — in the sense we use it today to identify branches — is possible. So it follows that we can trace our collective guilt back from internal combustion, to coal burning, to slash and burn agriculture and forest burning to create prairies, taming of fire and on back beyond hominids to the detestable act of respiration and gutsy methane production.

And beyond. The pseudoscience of Anthroapology is morphing into Apology for Life itself. Also known as bad religion. They’re getting a head start on the next campaign, apologizing for geology.

Parturient montes, nascetur ridiculus moleculo.
The mountains are in labor, a ridiculous molecule is the result.

It looks most of us here are agreed now that CO2 is not a factor in the warming of earth?
Yes?
Thanks.

Moving on then to rising H2O (g) as one of the main reasons. I can imagine that some of you would think that this must be it. However, the problem I have with this is that H2O (g) is also linked with cloud formation. My observations in this regard are:

1) cloudy day [in summer South Africa} Tmax can drop by as much as 8 degrees C
2) cloudy night [in winter South Africa] Tmin can rise by as much as 5 degrees C

So which one is more? I would say more H2O (g) also means more cloud and that means less energy IYOB.

It is a puzzle?

So what determines cloud formation? It is mostly the reactions TOA. At the moment we have lower magnetic field strengths on the sun
1) meaning more of the most energetic particles being released to hit earth
2) meaning more ozone, N-oxides and peroxides formed TOA
3) meaning less uv heat penetrating the atmosphere to heat the top layers of the oceans
4) meaning less clouds being formed.

It would seem to me now that the extra H2O (g) that we have in the atmosphere is slightly delaying the general cooling process that IMHO has already started [looking at global minimum temperatures]

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